HDR

Another bank holiday, another excuse to break out the geeky camera equipment. This time it's the panoramic tripod head and the new IR filter.

Navigate the three panoramic images above using the highlighted hotspots. There is a faux colour IR shot of the garden, a night edit version of the same photo and a faux HDR (single raw image) of a kitchen.

In my last post I showed some of the interesting effects that can be made with HDR. I tried to make it clear that the technique can also be used to create enhanced but realistic photos. As I explained, HDR is used to add additional light information to the photo which allows these extreme effects to be created. To demonstrate a more realistic processing I'm going to use the same starting image as last time:

Original

Software Edit

As can be seen in the original image the sky is overexposed while the shadows are very dark. While this can be edited in any decent photo software, the result will look similar to the right image. This edited image shows far more detail in the shadows and some more in the sky. This edit was only made possible due to the camera saving into a RAW format.

5 Image HDR

The final edit shows the same level of improvement over the original photo (in terms of detail) as the dramatic edits of the last post. The same type of processing is applied but less strongly allowing the photo to retain a more natural feel.

HDR stands for High Dynamic Range. HDR basically refers to an image having a range of brightnesses greater than the camera is capable of capturing, in a single photo. The way these are taken is with a series of exposures which with computer trickery are combined into a 32bit picture file. These cannot be displayed on normal computer screens/TVs so are 'photoshopped' back to a regular 16 or 8bit file. While this can give realistic results, it also allows for some wacky effects to be created.

I'm not going to go into the details on how to create these effects but will provide some links to tutorials at the bottom. I wanted to test the benefit of multiple exposure HDR over single exposure pseudo-HDR (the cheat method*). Additionally, I wanted to test how many exposures are needed for the best result. The three examples below show some of the effects HDR photography can lead to:

Single Vs Multiple Exposure HDR

There are times when either are appropriate but traditionally, the 'best' results will always come from a multiple exposure HDR. If there is movement in the scene you will get ghosting, which is the name given to the strange grey halos found around the moving objects (this can include plants/leaves moving in the wind). Software can reduce ghosting and in certain cases, remove it completely but a detailed tree scene on a windy day is going to have too much movement. *In these cases you can try single exposure HDR; this is only effective if you camera saves in RAW mode. Continue reading →